Keith Larson <k-larson2@NOSPAM.ti.com> wrote in message news:<3F4E2799.9050904@NOSPAM.ti.com>...> If you want to see what mars probably wont look like, but never the less > was derived from data through my telescope, have look here. This is a > simple stacking of a number of video frames with a little bit of > contrast and color push. I am still working on a filter that best > matches the data. > > http://home.houston.rr.com/klarson/mars2.jpgNice picture! I got a glimpse of Mars a couple of nights ago. Nothing like your picture, it was more like a white-hot lump, burning. Mars was so low in the sky and I viewed it over the village, so the hot air made it look like Mars was on fire, burning with huge flames. So I turned my scope to the north, and took a look at Saturn instead. I'm not sure, but I saw something that *may* be one of the moons. Rune
linear phase iir filters
Started by ●August 26, 2003
Reply by ●September 3, 20032003-09-03
Reply by ●September 3, 20032003-09-03
Jerry Avins wrote:> Keith Larson wrote: > >>Hello again Rune >> >> > ... > >>Somewhat related and interesting is that under the right conditions you >>can image surface detail in the moons of Jupiter using amateur scopes >>(check out the work by Ed Grafton). Visually seeing these moons as >>distinct disks against the sky is easy at 200x and above, but visually >>picking out surface detail is daunting. >> > > Yeah. I can make the moons out to be disks with my C5. Shake is a > problem with the "one tine fork", but I understand that the new model is > beefier. > >>On the DSP side, it is worth noting that for these brighter objects >>(planets) the method used is digital stabilization of the resulting AVI >>file. For my program I start with centroiding followed with >>correlation, but what I have found is that the correlation provides >>little additional benefit (usually turned off cause its slow). The >>greatest benefit comes when you can create a function that can select >>the best pictures to co-register. That part has been difficult. And my >>final goal is to directly attach to the video so I dont have to go to a >>really crappy VCR step. >> >>Another 'embedded DSP' solution that is just now beginning to catch on >>is adaptive optics. By this I am not talking about the adaptive optics >>that the big boys are using, but a more simplified tip/tilt/focus >>arrangement. >> > > Around 1950 (49?), when the color film was ASA 25, the cover of > Scientific American was a full-size color photograph of Jupiter. It > turned out to have been a single slide taken by an amateur astronomer > who was a professional servo engineer for an aircraft company. He > diverted part of the light to a four-quadrant photodetector, and fed the > X and Y outputs to the axes of an image-shifter plate. By keeping the > light centered on the detector, he kept it also stationary on the film, > preventing the image "dancing" caused by less-than-perfect seeing from > blurring the image. > > That was the first instance of image stabilization I know of in > astrophotography, amateur or professional. As a side benefit, limit > switches on the plate mechanism communicated with the tracking motors, > providing automatic guidance. I don't know how long your exposures are, > but would your pictures benefit from such a setup? > > I haven't disassembled my Canon IS binoculars (despite being tempted) > but I think they work on inertial, not image-position, inputs. If I'm > wrong, then the prism assembly from one of those will do the job. > Otherwise, I'd find it fun to try my hand.Hey Jerry and Keith, I really like this thread, and have no personal experience with image stabilization. I was wondering if those MEMS mirrors TI makes would work to remove air "twinkle" in an amature 'scope. You'd still need a servo loop for tracking the center of the planet in questions, but the tiny mirrors could be programmed by observing the previous image and correcting for the next expected one. I don't know if it'd work, but it seems like you're the guys who could do it! Patience, persistence, truth, Dr. mike -- Mike Rosing www.beastrider.com BeastRider, LLC SHARC debug tools
Reply by ●September 4, 20032003-09-04
Rune Allnor wrote: ...> So I turned my scope to the north, and took a look at Saturn instead. > I'm not sure, but I saw something that *may* be one of the moons.The joys of amateur astronomy! :)
Reply by ●September 4, 20032003-09-04
Hello Rune Up early in the morning I see (I was asleep). Unlike Jupiter where the moons are obvious, both bright and in a line, the moons of Saturn are dimmer and tipped relative to an Earth based view making them easy to confuse with background stars. What is needed is a program that plots the view so you can seperate the moons from the stars. Using this technique you can nab a half dozen or more in a decent sized scope. One thing you probably did not see (when looking at Mars) is Demos and Phobos. These are a bit trickier, requiring an occulting bar and a program that tells you where to expect to see them. I glimpsed these two moons for the first time this last Thursday night at around 1AM using the George Observatories 36" Ritchie-Chretien Cassegrain telescope. BTW, I volunteer a lot of my time to the G.O. which is part of the Houston Museum of Natural Science. Not exactly an 'amateur' telescope, but these moons were so obvious that Im fairly certain I would be able to nab them with my own scope. What it takes is an occulting bar to block the light of the planet which is quite bright compared to the moons. And by the way, the same trick also works for Saturn. Heck, mayeb one or two of Jupiters minor moons is possible? Nabbing these digitally would be a cinch, but not nearly as glamorous as a photo of the planet itself. Best regards, Keith Larson ------------------------------- Rune Allnor wrote:> Keith Larson <k-larson2@NOSPAM.ti.com> wrote in message news:<3F4E2799.9050904@NOSPAM.ti.com>... > > Nice picture! I got a glimpse of Mars a couple of nights ago. Nothing > like your picture, it was more like a white-hot lump, burning. Mars was > so low in the sky and I viewed it over the village, so the hot air made > it look like Mars was on fire, burning with huge flames. > > So I turned my scope to the north, and took a look at Saturn instead. > I'm not sure, but I saw something that *may* be one of the moons. > > Rune+------------------------------------------+ |Keith Larson | |Member Group Technical Staff | |Texas Instruments Incorporated | | | | $150 TMS320VC33 DSK's ARE NOW AVAIALBLE | | 281-274-3288 | | k-larson2@ti.com | |------------------------------------------+ | TMS320C3x/C4x/VC33 Applications | | | | TMS320VC33 | | The lowest cost and lowest power | | floating point DSP on the planet! | | 500uw/Mflop | +------------------------------------------+
Reply by ●September 4, 20032003-09-04
Keith Larson <k-larson2@NOSPAM.ti.com> wrote in message news:<3F577B3F.8090205@NOSPAM.ti.com>...> Hello Rune > > Up early in the morning I see (I was asleep).Actually, no. It was between 11 and 12 PM. I'm at 67 degrees north, so Mars just makes it above the horizon (and the hills) a few hours around midnight. At that time Saturn rises above the horizon to the north. Fortunately, there are fewer houses and mountains to the north, so the seeing is way better towards Saturn than Mars.> Unlike Jupiter where the moons are obvious, both bright and in a line, > the moons of Saturn are dimmer and tipped relative to an Earth based > view making them easy to confuse with background stars. What is needed > is a program that plots the view so you can seperate the moons from the > stars. Using this technique you can nab a half dozen or more in a > decent sized scope.My scope is nowhere near decent in astronomical terms. It's a 80 mm spotting scope with a 20-60x zoom eyepiece. Whatever I saw near Saturn may wery well have been in the plane of the rings. Its apparent distance was some 8 to 10 ring diameters from Saturn itself.> One thing you probably did not see (when looking at Mars) is Demos and > Phobos. These are a bit trickier, requiring an occulting bar and a > program that tells you where to expect to see them.Nowhere near! Those guys are quite small? Some 20 or 30 km across?> I glimpsed these two moons for the first time this last Thursday night > at around 1AM using the George Observatories 36" Ritchie-Chretien > Cassegrain telescope. BTW, I volunteer a lot of my time to the G.O. > which is part of the Houston Museum of Natural Science. Not exactly an > 'amateur' telescope, but these moons were so obvious that Im fairly > certain I would be able to nab them with my own scope. What it takes is > an occulting bar to block the light of the planet which is quite bright > compared to the moons. And by the way, the same trick also works for > Saturn. Heck, mayeb one or two of Jupiters minor moons is possible?I saw Jupiter last winter. The four largest moons were clearly visible. I even think I saw some of the bands in the atmosphere, but that may just be wishful thinking.> Nabbing these digitally would be a cinch, but not nearly as glamorous as > a photo of the planet itself.Well... the chance to get images of Mars' moons don't come every day... it may well be seen as a greater achievement by those "in the know" than a nice, glamorous and stunning image of Mars itself. It's been raining for three days straight, now. No hope of any astronomy for the next few days. Hopefully, the aurora will not be too bright the next clear night... Rune
Reply by ●September 5, 20032003-09-05
Hello again Rune> >>Nabbing these digitally would be a cinch, but not nearly as glamorous as >>a photo of the planet itself. >> > > Well... the chance to get images of Mars' moons don't come every day... > it may well be seen as a greater achievement by those "in the know" than > a nice, glamorous and stunning image of Mars itself.Actually I was only referring to simply detecting the moons of Mars using digital techniques. These moons are teeny tiny small! The planet itself is the one to take pictures of. Somewhat related and interesting is that under the right conditions you can image surface detail in the moons of Jupiter using amateur scopes (check out the work by Ed Grafton). Visually seeing these moons as distinct disks against the sky is easy at 200x and above, but visually picking out surface detail is daunting. On the DSP side, it is worth noting that for these brighter objects (planets) the method used is digital stabilization of the resulting AVI file. For my program I start with centroiding followed with correlation, but what I have found is that the correlation provides little additional benefit (usually turned off cause its slow). The greatest benefit comes when you can create a function that can select the best pictures to co-register. That part has been difficult. And my final goal is to directly attach to the video so I dont have to go to a really crappy VCR step. Another 'embedded DSP' solution that is just now beginning to catch on is adaptive optics. By this I am not talking about the adaptive optics that the big boys are using, but a more simplified tip/tilt/focus arrangement. Best regards, Keith Larson +------------------------------------------+ |Keith Larson | |Member Group Technical Staff | |Texas Instruments Incorporated | | | | 281-274-3288 | | k-larson2@ti.com | |------------------------------------------+ | TMS320C3x/C4x/VC33 Applications | | | | $150 TMS320VC33 DSK's ARE AVAILABLE NOW | | | | TMS320VC33 | | The lowest cost and lowest power | | floating point DSP on the planet! | | 500uw/Mflop | +------------------------------------------+
Reply by ●September 5, 20032003-09-05
Keith Larson wrote:> > Hello again Rune >...> > Somewhat related and interesting is that under the right conditions you > can image surface detail in the moons of Jupiter using amateur scopes > (check out the work by Ed Grafton). Visually seeing these moons as > distinct disks against the sky is easy at 200x and above, but visually > picking out surface detail is daunting.Yeah. I can make the moons out to be disks with my C5. Shake is a problem with the "one tine fork", but I understand that the new model is beefier.> > On the DSP side, it is worth noting that for these brighter objects > (planets) the method used is digital stabilization of the resulting AVI > file. For my program I start with centroiding followed with > correlation, but what I have found is that the correlation provides > little additional benefit (usually turned off cause its slow). The > greatest benefit comes when you can create a function that can select > the best pictures to co-register. That part has been difficult. And my > final goal is to directly attach to the video so I dont have to go to a > really crappy VCR step. > > Another 'embedded DSP' solution that is just now beginning to catch on > is adaptive optics. By this I am not talking about the adaptive optics > that the big boys are using, but a more simplified tip/tilt/focus > arrangement.Around 1950 (49?), when the color film was ASA 25, the cover of Scientific American was a full-size color photograph of Jupiter. It turned out to have been a single slide taken by an amateur astronomer who was a professional servo engineer for an aircraft company. He diverted part of the light to a four-quadrant photodetector, and fed the X and Y outputs to the axes of an image-shifter plate. By keeping the light centered on the detector, he kept it also stationary on the film, preventing the image "dancing" caused by less-than-perfect seeing from blurring the image. That was the first instance of image stabilization I know of in astrophotography, amateur or professional. As a side benefit, limit switches on the plate mechanism communicated with the tracking motors, providing automatic guidance. I don't know how long your exposures are, but would your pictures benefit from such a setup? I haven't disassembled my Canon IS binoculars (despite being tempted) but I think they work on inertial, not image-position, inputs. If I'm wrong, then the prism assembly from one of those will do the job. Otherwise, I'd find it fun to try my hand. Jerry -- Engineering is the art of making what you want from things you can get. �����������������������������������������������������������������������
Reply by ●September 5, 20032003-09-05
"Jerry Avins" <jya@ieee.org> wrote in message news:3F58BE2E.76283D4D@ieee.org...> Keith Larson wrote: > > > > Hello again Rune > > > ... > > > I haven't disassembled my Canon IS binoculars (despite being tempted) > but I think they work on inertial, not image-position, inputs. If I'm > wrong, then the prism assembly from one of those will do the job. > Otherwise, I'd find it fun to try my hand.On my Canon IS SLR camera lens, the stabilization is definitely inertial. I would assume the same technique is used on the binoculars.
Reply by ●September 5, 20032003-09-05
> That was the first instance of image stabilization I know > of in astrophotography, amateur or professional. Yep, I have seen that picture and I have to admit that is pretty good even by todays standards. What a lot of people miss is that this was done using photographic film to collect the light and therefor over a fairly long exposure period of time. Tough to do when you dont have video camera, digitizer and high performance micro-processor! Nowadays collecting light from bright objects using very short exposures is really paying off in the ability to freeze a wobbly image. All you need to do is digitally select the best images and sum them together. There are examples of people imaging the ISS with enough detail that you can see the seems in the solar panels! > I haven't disassembled my Canon IS binoculars (despite being tempted) but I think they work on inertial, not image-position, inputs. If I'm > wrong, then the prism assembly from one of those will do the job. Otherwise, > I'd find it fun to try my hand. > This is probably not going to work for a telescope since the intertial magnitude of a 100x telescope view is considerably smaller than when at 10-20x. Also, the majority of the telescopic problems are atmospheric, so there is no inertia to work with. I am afraid that for a telescope we are back to the optical sensor and servo system. Santa Barbara Instruments Group (SBIG) has been selling this system for several years now but to be honest, I think a smarter system is possible. BTW, a saw a cheaper Russians made image stabilizing binocular that apparently used a weight and canteliever tied to, probably, one of the prisms. On the other hand, the Canon IS needs a battery to run the micro-processor that gets information from an eccelerometer that eventualy drives a servo that is attached to a prism. BTW, I hate to admit this, but ADI has a really cool solid-state micro-machine accelerometer that you can find in a number of products ranging from joy-stick controls for PC-games to air-bag sensing. +------------------------------------------+ |Keith Larson | |Member Group Technical Staff | |Texas Instruments Incorporated | | | | 281-274-3288 | | k-larson2@ti.com | |------------------------------------------+ | TMS320C3x/C4x/VC33 Applications | | | | $150 TMS320VC33 DSK's ARE AVAILABLE NOW | | | | TMS320VC33 | | The lowest cost and lowest power | | floating point DSP on the planet! | | 500uw/Mflop | +------------------------------------------+
Reply by ●September 5, 20032003-09-05
Hi Mike> Hey Jerry and Keith, > > I really like this thread, and have no personal experience with image > stabilization. I was wondering if those MEMS mirrors TI makes would > work to remove air "twinkle" in an amature 'scope. You'd still need > a servo loop for tracking the center of the planet in questions, but > the tiny mirrors could be programmed by observing the previous image > and correcting for the next expected one. > > I don't know if it'd work, but it seems like you're the guys who could > do it! > > Patience, persistence, truth, > Dr. mikeNo, or at least not the DLP type of mirrors. The mirrors in a DLP are flipped on/off at a very high rate effectively giving a PWM that when you are turning on and off a light becomes a gray-scale. The PWM is pretty simple too. Here is how that works. Suppose you have an 8 bit gray scale pixel value as shown below. The MSB, which carries the most important information basically turns on/off the mirror for 50% of the time. The next bit 25%, then 12.5% and so on. Therefor all you really need is a shift register that clocks the data out to drive the DLP mirror at the right time. 7 0 +--+--+--+--+--+--+--+--+ PixVal |MS| | | | | | |LS| +--+--+--+--+--+--+--+--+ |<----- 8ms ---->|<-4ms-->| 2ms| 1| ||| LSB is +----------------+--------+----+--+-+++ to small! | MS | | | | ||| +----------------+--------+----+--+-+++ Best regards, Keith Larson +------------------------------------------+ |Keith Larson | |Member Group Technical Staff | |Texas Instruments Incorporated | | | | 281-274-3288 | | k-larson2@ti.com | |------------------------------------------+ | TMS320C3x/C4x/VC33 Applications | | | | $150 TMS320VC33 DSK's ARE AVAILABLE NOW | | | | TMS320VC33 | | The lowest cost and lowest power | | floating point DSP on the planet! | | 500uw/Mflop | +------------------------------------------+
